#include <stdio.h>
#include <math.h> 
int main() { 
    double a,b,c,s,area; 
    a=3.67; 
    b=5.43;  c=6.21; 
    s=(a+b+c)/2; 
    area=sqrt(s*(s-a)*(s-b)*(s-c)); 
    printf("a=%f\tb=%f\tc=%f\n",a,b,c);  
    printf("area=%f\n",area);  }